The present invention relates to heat pump equipment.
In previously proposed heat pump equipment, means have been provided to enable heat exchangers outside a building to be defrosted even while the equipment is being used to transfer heat from outside the building into its interior, in the form of more than one pressure drop and complex solenoid operated valve systems. This has made the equipment relatively expensive, and, because of its complexity, relatively difficult to diagnose any malfunction occurring within the equipment.
A first aspect of the present invention seeks to obviate this disadvantage.
Accordingly, a first aspect of the present invention is directed to heat pump equipment comprising at least three heat exchangers, one of which is intended to be located in an enclosed region and the other two of which are intended to be located outside the enclosed region, in which each heat exchanger has a delta connection end connected in heat-exchange fluid communication with a delta arrangement, such that the delta connection end of each heat exchanger is connected to both of the delta connection ends of the other two heat exchangers via the delta arrangement, in which arrangement there are three fluid-expansion devices, one between the two connections of each pair of adjacent connections of the heat exchangers to the delta arrangement.
Such equipment has the advantage that heat-exchange fluid can be directed to flow from the two outside heat exchangers to the inside heat exchanger, or alternatively from the inside heat exchanger to the two outside heat exchangers, and for defrosting of either one of the outside heat exchangers, fluid can be directed to flow from both that one of the outside heat exchangers and the inside heat exchanger to the other outside heat exchanger via the delta arrangement.
To achieve this, there is preferably one compressor connected to receive heat-exchange fluid from and to feed heat-exchange fluid to the heat exchangers via a valve arrangement.
The valve arrangement may comprise a valve for each heat exchanger. Each valve may be a four-way valve.
Equipment embodying this first aspect of the present invention may be easier to service than previously proposed equipment. Use of the gas phase to effect defrosting of the outside coils allows defrost rates to be unaffected by gravity especially defrost rates of each path of multiple path heat exchangers if these are used. This speeds defrosting by an even distribution of heat. The path length does not need to be reduced when one of the outside heat exchangers is defrosted. This increases the maximum performance in the event that a refrigerant with a glide is used.